Sulfur vaporization



Patented May 16, 1950 UNITED STATES PATENT OFF-HIE...

SULFUR VAPOR/IZATION Application April 21, 1945, Serial No. 589,679

13 Claims. (01. 23-224) This invention relates to method and apparatusfor vaporizin and superheating sulfur.

-Viasporization of sulfur and superheating of sulfur vapors are two ofthe most difficult problems encountered in chemical operations. Sulfurordinarily contains a small amount of both organic and inorganicimpurities which deposit on the vaporizing surface when sulfur isvaporized causing formation of coke and scale deposits which necessitatefrequent cleaning of the still in order to obtain satisfactory heattransfer rates without exceeding safe metal temperatures. In superheating sulfur vapors the principal difficulty is encountered in thecorrosive effect of sulfur on all common metals and alloys at elevatedtemperature. Not only is the life of the heating element shortened, butscale formation on the surface of the heating elements greatly reducesthe heating transfer rates. Many chemical syntheses involving use ofsulfur would be possible if a satisfactory method and apparatus forvaporizing and superheating sulfur was available.

An object of this invention is to provide an apparatus for vaporizingsulfur.

,A furtherv object of the invention is to provide a method and apparatusfor superheating sulfur vapors without any substantial corrosion of theapparatus.

Further objects of this invention will manifest themselves from thefollowing description and the accompanying drawings, of which Figure 1is a diagrammatic elevational view of one form of apparatus for carryingout the invention; and Figure 2 a diagrammatic'elevational view ofanother form of apparatusfor carrying out the invention..

Referring to. Figure 1, the numeral l designates apump by means of whichmolten sulfur at a, temperature between approximately 250 and 300 F. ispumped throuh line 2 into vaporizing and superheating column or chamber3. Column 3 is lined with refractory material such as carborundum,alundum, quartz, fire brick, or the like, which is not attacked bysulfur to any substantial extent. Column 3 is filled with a bed ofpelleted; fragmentary or granular refractory material such ascarborundum, alundum, quartz or fire brick, heatedto a temperaturesomewhat above the temperature to which it is desired to superheatsulfur vapors. Upon contact of the molten sulfur with the moving bed ofrefractory material the sulfur is vaporized and passes upward throughthe bed in direct heat exchange with the hot refractory material andbecomes REESSUED heated to the desired temperature. The superheatedsulfur vapors leave thetop of chamber 3 through line 4 and are chargedto a system in which it is desired to use the superheated sulfur vapors,such as for example a reactor for making carbon disulfide by reaction ofsuperheated sulfur vapors with methane, or other hydrocarbon gases, inthe presence of a suitable catalyst such as silica gel, activatedalumina, activated clay or synthetic silica-alumina catalyst. The moltensulfur enters the chamber 3 preferably some distance from the bottomthereof, but below the middle of the column.

superheated steam is admitted to the bottom of the column 3 throughvalve-controlled pipe 5 at a temperature of approximately 900-950"- F.in order to purge residual sulfur from the refractory material. Anoutlet 6 is :provided between the line 5 and line 2 for drawing off thesteam and sulfur vapors contained therein from the purged refractorymaterial. The line 6 is connected to a condenser I maintained underatmospheric or superatmospheric pressure. Water, steam and sulfur inmolten form pass from the condenser E to the receiver 8. Sufficientpressure may be maintained in the condenser and receiver 8 so thatsubstantially all the steam and sulfur is condensed to liquid or moltenstate. Pressure in the column 3 will be somewhat above that maintainedin the condenser so that the purging steam and sulfur vapors containedtherein will pass through line 6 instead of passing upward through thecolumn 3 to the outlet 4. It will be understood, of course, that acertain portion of the purging steam will pass ulpward through column 3and. be eliminated through line 4. From the receiver 8 molten sulfur isrecycled through line 9 by meansof pump l0 through line H controlled byvalve 12 to line 2. Hot water and steam are withdrawn from" the upperportion of receiver 8 through valve-controlled line I3.

Hot refractory material is intermittently introduced into the vaporizerand superheater 3 from hopper l4 through line [5 controlled by valve 16.The refractory material is intermittently withdrawn from the bottom ofcolumn 3 through line H controlled by valve I7 and passes to hopper l8.At such time as hopper I4 is being emptied into column 3, valve ill inthe outlet of hopper l8 and valve 20 in the inlet to hopper II areclosed. Refractory material is preferably withdrawn from column 3 intohopper l8 at the same time as hopper I4 is emptied in column 3. Whenhopper M is empty and hopper I8 is full of refractory material valve E6in the outlet of hopper l4 and valve I? in the inlet to hopper 53 areclosed and the flow of refractory material in the chamber 3 isinterrupted. Any steam which accumulates in the hopper i8 is removedfrom the top thereof through valve-controlled line 2! after whichrefractory material from hopper I8 is discharged therefrom through valveI9 and the refractory material passes into receiver 22.

During the time that steam is withdrawn from the hopper l8 hopper 'M isdepressured and sul fur is withdrawn therefrom 'through'valve-controlled line 23. The sulfur vapors may be condensed andrecycled to line 2 through a line not shown. Valve 25 is then opened andhopper i3 is then rechargedwith hot refractory material from receiver 24through valve 25. hopper I4 is filled with hot refractory material valve20 isclosed and any flue gas which may have accumulated in hopper M isexhausted therefrom through valve-controlled line 23. Hopper" I4 is thenpressured with sulfur vapors from line 4 by opening valve 25 in line 25and permitting sulfur vapors to flow into the hopper I4. When thepressure between chamber 3 and hopper [4 has been equalized valve i isagain opened and the refractory material is permitted to flow from thehopper l4 into top of chamber 3 and valve I1 is opened to permitrefractory material to be withdrawn from the bottom of chamber 3.

From the receiver 22 granular refractory material passes continuouslythrough line 21 to elevator 28, which may be of the bucket, or any othersuitable type, and is conveyed to kiln 28 through line 30. Therefractory material passes downwardly through kiln 29 and is heatedduring its downward passage to the desired temperature by burning in thekiln combustible gases mixed with air charged thereto through manifold3i and valve-controlled lines 32, 33, 34, 35, and 36 at spaced pointsalong the kiln. Any suitable liquid, powdered or gaseous fuel may beburned in the kiln 29 such as natural or producer gas, furnace oil, acidsludge, or tar. A portion of the heat may be supplied by combustion oforganic matter deposited on the refractory material during the sulfurvaporization step. Some crude sulfurs contain substantial amounts oforganic matter which is removed during the vaporization and superheatingstep and left deposited in the form of coke on the refractory material.This organic matter is burned from the refractory material in kiln 29'by supplying sufficient excess of air to burn the organic matter. Fluegases leave the kiln 29 through valve-controlled lines 31, 38, 39, 40and M. The heated refractory material leaves the bottom of the kilnthrough line 42 controlled by valve 43 and is carried by elevator 44 toline 45 which empties into the top of receiver 24. Any residual flue gasin the heated refractory material is withdrawn from receiver 24 throughvalve-controlled line 49.

In the apparatus just described, in addition to the vaporizing andsuperheating chamber 3, hoppers l4 and H! are preferably lined withrefractory material, as well as such other portions of the apparatuswhich come in direct contact with sulfur vapors at high temperature.

Instead of purging the refractory material by injecting superheatedsteam through line 5 into the bottom of chamber 3 and withdrawing thesteam and contained sulfur vapor through line 6, the refractory materialmay be purged in hop- As soon as per l8 by injecting superheated steaminto the bottom thereof through valve-controlled line 41 and withdrawingthe steam with its sulfur content from the top of hopper l8 throughvalve-controlled line 58 which, in turn connects to line 6.

It will be apparent that the apparatus shown in Figure 1 may be used topurify contaminated sulfur. In such case the refractory material will beheated to a temperature sufficient only to vaporize the sulfur. Suchtemperature may be approximately 1000 to 1100 F.

Referring now to Figure 2, solid sulfur in small pieces or in powderedstate isfed from hopper 51]: through valve 5| by means of screw conveyerto a Sulfur melter 53. The sulfur is melted in melter 53 by directcontact with superheated steam or hot water under pressure. Sulfur ischarged to the melter 53 intermittently. When the melter is filledwith'sulfur, valve 5! is closed and superheated steam is introduced intothe bottom of melter 53 through valve controlled line 55. Melted sulfurand water are transferred from the bottom of melter 53 through line 55controlled by valve 56 to a sulfur-water separator 51. Valve 56 is thenclosed and melter 53 depressured by opening valve on line 51 on the topof the melter to permit steam to escape and is then recharged by openingvalve 5i and operating screw conveyer 52. Since melter 53 is operatedintermittently it should be made sufliciently large to provide asufficient supply of molten sulfur for separator 51 so as to enablesulfur vaporizing said superheating operation to be carried oncontinuously.

Water is removed from the top of separator 51 through valve-controlledline 58. Molten sulfur at a temperature of approximately 250-275 F. iswithdrawn from the bottom of separator 51 through line 59 by means ofpump 6|! and pumped through line 6! into vaporizer and super-heaterchamber 62 at a point below the middle thereof, but some distance fromthe bottom thereof. Molten sulfur is discharged into chamber 62 througha suitable distributing device and contacts a hot moving bed ofpelleted, granular or fragmentary refractory material which vaporizesthe sulfur and superheats it to the desired temperature. The superheatedsulfur vapor leaves the top of chamber 52 through lines 63 and 64.

superheated steam at a temperature of approximately BOW-950 F. isintroduced into the bottom of vaporizing and superheating chamber 62through valve-controlled line 65 to purge the refractory material ofsulfur. The sulfur vapor and steam leave the chamber 62 through line 68and are returned to sulfur melter 53. The sulfur condenses in melter 53and the steam wholly or partially condenses to water at the same time asthe solid sulfur is heated to the melting point. Only sufiicientsuperheated steam is admitted to the melter 53 through line 54 to supplyheat in addition to that supplied through line 66 necessary for meltingsulfur in melter 53.

Refractory material leaves the bottom of chamber 62 through either lines61 or 68 controlled by valves 59 and 10, respectively. If valve 10 isclosed and valve 69 is open the refractory material will pass intohopper H. While refractory material is passing into hopper ll, valve 12in the outlet 13 connected to the bottom of hopper ii is closed. Whilerefractory material is flowing from chamber 52 into hopper H, refractorymaterial is flowing from hopper I4 through line 15 controlled by valve'16 to the bottom of elevator 11. Elevator 11 is of the bucket, or anyother suitable type.

amazes Afterhopper M is emptied, valve =16 is closed and valve 10 isopened to permit the refractory material to pass from the bottom ofchamber 62 through line 68 into hopper 1'4. 1 As soon as hopper "I4 isfull of refractory material, valve 10 is closed and any steamaccumulated in hopper T4 is withdrawn through valve-controlled pipe 11'.

After hopper II is filled with refractory material, valve 69 is closedand the hopper is depressured by drawing off steam throughvalvecontrolled line 18. Valve l2 is then opened and the refractorymaterial passes from hopper "H through line 13 to the elevator H. Inthis way refractory material is continuously withdrawn from chamber 62through either hopper H orhopper l4 and supplied continuously to theelevator 11.

Instead of purging sulfur from the refractory "material by admittingsuperheated steam into the bottom of chamber 92, sulfur maybe purgedfrom the refractory material in hoppers H and 1-4 by admittingsuperheated steam into the bottom thereof through valve-controlled lines19 and :80, respectively, and withdrawing the steam and sulfur vaporsfrom the top of hoppers I I and 14 through valve-controlled lines 'BI'and 82, respectively. From the line 8! the steam and sulfur vapors passto line '66 and then to sulfur'melter 53.

Refractory material is charged from the top of the elevator 11 throughline 83 to kiln 84. Kiln 84 is heated by means of a mixture of air andcombustible gas, liquid or powdered fuel introduced at spaced pointsthrough valve-controlled lines 85 and 86. Combustion gases are withdrawnfrom the kiln through valve-controlled lines -81, 8'8 and 89. Ifdesired, combustion gases "from the kiln may be circulated through theelevator H and withdrawn "from the top thereof through valve-controlledline 90 in order to preheat therefractory material before it isintroduced into the top of the kiln. If for example, the refractorymaterial is heated to approximately 1400 F. in thekiln, it may bepreheated 'to approximately 1200 F. in the elevator by circulating theflue gases therethrough. Heated refractory material leaves the bottom ofthe kiln 84 through either lines 91 or 92 controlled by "valves98 and94, respectively. When refractory material is discharged from the kilnthrough line 9% into hopper 95, valve 95 in the outlet '9? f hopper 9i:will be closed. Valve 94 in the inlet 92 to hopper 98 will be closed,and valves 99 the outlet 1-90 of hopper '99 will open so that refractorymaterial'canflow from hopper 98 continuously into the top of thevaporizer and superheater 52. As soon as hopper 98 is empty, valve 99and valve [ill in line I02 are closed and sulfur vapors are exhaustedfrom the hopper through valve-controlled line I03. Sulfur vaporsexhausted through line I03 may be recycled before or after condensationto separator by means of a line not shown. After hopper 98 isdepressured valve 94 is opened to permit hot refractory material to flowfrom kiln 84 into the hopper.

Hopper 95 is filled with hot refractory material during the period thatrefractory material is fed from hopper 98 into the chamber 62. Afterhopper 95 is filled, valve 93 is closed and hopper 95 is pressured withsulfur vapors through line I04, controlled by valve I05, connected toline 63. Hopper 95 is now ready to feed hot refractory material tochamber 62 by opening valve 96.- Hopper 95 is exhausted of sulfur vaporthrough valve -contro'lled line I06 whenit is empty and the sulfurvapors may be recycled to separator 51. Hopper 98 is pressured byadmitting sulfur vapors thereto through line I02 controlled ;'by valveI'M after it is filled and valve 94 has been closed.

Flue .gas may be removed from the refractory material in hoppers 95 and98 throughvalve-controlled lines 106 and H13, respectively, prior torepressuring with sulfur vapors.

It will be understood inconnection with Figure 1 that the purging steamwith contained sulfur vapors may be used to melt solid sulfur, as de--'scribccl connection with Figure 2, and that sul- :fur melting inFigure 2 by means of the purging steam may be omitted and sulfur meltedby extraneous heating means only.

The method and apparatus described and shown in connection with Figure 2have the advantage over those described and shown :in Figure :1, that inFigure 1 the temperature to which the refractory material can be heatedis limited by the ability of the metal of which the elevator isconstructed to withstand high temperatures. At the present time,materials available for such construction are capable of standing a,maximum temperature o'fabout 1200" F. with the result that the limit towhich the refractory material can be heated is about 1200 F. and thetemperature to which sulfur can be heated by means of .the refractorymaterial is somewhat below 1200 F.

The apparatus of Figure 2 is not limited as to temperature because theheating kiln follows the elevator. Therefore, much higher sulfur vaportemperatures can be attained in conjunction with the construction shownin Figure 2.

In both Figures 1 and :2. all parts which come in contact with hotsulfur vapors are preferably made of or lined with refractory materialwhich is not substantially attacked by sulfur.

In both Figures 1 .and 2 the flow rate of refractorymateriaLl throughthe vaporizing and superhe'ating chamber, and the quantity of sulfurcharged is :so regulated that the temperature of theirefractory materialleaving the'bottom of the chamber is above the vaporizing temperature ofsulfur at existing pressure.

As an example of an operation carried. out in the apparatus shown inFigure 2, alundum, as the refractory, in the form of 6 to 10 mesh sizefragments is heated to 1400" F. in the kiln 89 by the combustion ofnatural gas. The granular alundum moves continuously through the kilnand passes to either hopper 9501" 98 and therefrom as previouslyexplained through chamber 62. Molten sulfur at a temperature of 270 F.is pumped continuously through line 6| to chamber 62 wherein oncontacting the moving granular alundum it is vaporized and superheatedto 1200 F. before leaving chamber 62 through lines 63 and 64. Moltensulfur is charged to 62 at the rate of 24.7 pounds of sulfur per hourand granular alundum passes through chamber 62 at the rate of 1 cubicfoot per hour. Steam at 900 F. is introduced into chamber 62 throughline 65. This steam amounts to about 3% by weight of the sulfur chargedto chamber 62. The temperature of the alundum particles leaving throughthe bottom of 62 is 900 F.

It is claimed:

1. The method of vaporizing sulfur comprising circulating solidcomminuted material resistant to sulfur attack through a heater andvaporizer,

heating said material, to a temperature above the boiling point ofsulfur in said heater by direct contact with hot combustion gases,removing combustion gases from the treated material, charging the hotmaterial to a vaporizing zone, charging sulfur to be vaporized tosaidvaporizing zone in direct contact with said hot material,withdrawing sulfur vapors from said vaporizing zone, withdrawing saidmaterial from the vapor izing zone before the temperature of thematerial falls below the boiling point of sulfur, recycling thewithdrawn material to the heater and pureing sulfur from said materialprior to recycling it to the heater.

2. Method in accordance with claim 1 in which said material passesthrough the heater and vaporizer in the form of a moving bed.

3. Method in accordance with claim 1 in which said material passescontinuously through the heater and vaporizing zone in the form of amoving bed.

4. Method in accordance with claim. 1 in which the comminuted materialis mechanically nveyed from the heater to the vaporizing zone.

5. Method in accordance with claim 1 in which the comminuted material ismechanically conveyed from the vaporizing zone to the heater and iscaused to flow by gravity from the heater to the vaporizing zone.

6. The method of vaporizing sulfur comprises heating comminutedrefractory material to a temperature above the boiling point of sulfurby direct contact with hot combustion gas, separating combustion gasfrom the hot refractory material, charging said hot refractory materialto a vaporizing zone lined with refractory material, charging moltensulfur to said vaporizing zone in direct contact with said hotrefractory material, contacting said sulfur and refractory material fora period of time sufficient to vaporize the sulfur and superheat thevapors, withdrawing superheated sulfur vapors from the vaporizing zonewithdrawing said comminuted refractory material from said vaporizingzone at such rate as to remove it from said zone before its temperaturedrops below the boiling point of sulfur, recycling the withdrawnrefractory material to the heater and purging sulfur from saidrefractory material prior to recycling it to the heater.

7. Method in accordance with claim 6 in which superheated steam is usedto purge sulfur from the refractory material and the resultingsteamsulfur vapor mixture is used to melt sulfur to be charged to thevaporizer.

8. Method in accordance with claim 6 in which the comminuted refractorymaterial is heated to approximately 1200 F. before charging it to thevaporizing zone.

9. Method in accordance with claim 6 in which the comminuted refractorymaterial is heated to approximately 1400 F. prior to charging it to thevaporizing zone.

10. The method of vaporizing sulfur comprising, alternately heatingcomminuted solid material not reactive with sulfur at temperatures ofboiling sulfur to a temperature substantially above the boiling point ofsulfur and contacting said heated material with sulfur to be vaporized,discontinuing contact of sulfur with said solid material before thetemperature thereof is reduced below the boiling temperature of sulfur,purging residual sulfur from the solid material and repeating theheating of the solid material and the vaporization of sulfur therewith.

11. The method of vaporizing sulfur comprising, circulating comminutedsolid material not reactable with sulfur at temperatures of boilingsulfur through a heating and vaporizing zone, heating said material insaid heating zone to a temperature substantially above the boiling pointof sulfur, passing said heated material to said vaporizing zone andthere contacting with sulfur to be vaporized, withdrawing sulfur vaporsfrom said vaporizing zone, Withdrawing said material from saidvaporizing zone before the temperature thereof is reduced below theboiling temperature of sulfur, purging residual sulfur therefrom andrecycling said material to said heating zone.

12. The method in accordance with claim 11 in which the solid materialis a refractory material.

13. The method in accordance with claim 11 in which the sulfur iscontacted with a hot material in a moving bed of the material.

CHARLES A. PORTER. MILTON M. MARISIC.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 91,313 Divine June 15, 1889873,812 Walter Dec. 1'7, 1907 1,712,082 Koppers May 7, 1929 1,738,890Goodrich Dec. 10, 1929 2,030,885 Maxim Feb. 18, 1936 2,113,230 CecconApr. 5, 1938 2,348,699 Tuttle May 9, 1944

10. THE METHOD OF VAPORIZING SULFUR COMPRISING, ALTERNATELY HEATINGCOMMINUTED SOLID MATERIAL NOT REACTIVE WITH SULFUR AT TEMPERATURES OFBOILING SULFUR TO A TEMPERATURE SUBSTANTIALLY ABOVE THE BOILING POINT OFSULFUR AND CONTACTING SAID HEATED MATERIAL WITH SULFUR TO BE VAPORIZED,DISCONTINUING CONTACT OF SULFUR WITH SAID SOLID MATERIAL BEFORE THETEMPERATURE THEREOF IS REDUCED BELOW THE BOILING TEMPERATURE OF SULFUR,PURGING RESIDUAL SULFUR FROM THE SOLID MATERIAL AND REPEATING THEHEATING OF THE SOLID MATERIAL AND THE VAPORIZATION OF SULFUR THEREWITH.